TECHNICAL FIELD
[0001] The present invention relates to a catalyst employed in a reaction for obtaining
highly pure 1,3-butadinene by selectively hydrogenating acetylene compounds contained
in a C4 hydrocarbon compound reservoir which mainly contains 1,3-butadiene; a method
of producing the catalyst; and a method of using the catalyst.
BACKGROUND ART
[0002] A variety of olefin compounds used as basic raw material in the petrochemical industry
are usually produced by steam cracking of naphtha. Since such olefin compounds contain
highly-unsaturated hydrocarbon compounds, in order to utilize them as a raw material
in the macromolecular chemical industry, such hydrocarbon compounds must be removed.
In order to produce olefin compounds such as ethylene, propylene, butadiene and isoprene
and other similar compounds, it is required to minimize the loss of useful materials
in the feed flow, such as ethylene, propylene, butanes, butadiene, isoprene and other
similar compounds, and to remove various acetylene-type impurities such as acetylene,
methylacetylene, vinylacetylene, ethylacetylene; 2-methyl-1-butane-3-ene and other
similar compounds from a mixed reservoir of unpurified C2 to C5 compounds.
[0003] Examples of a method of removing such highly-unsaturated hydrocarbon compounds include
a method in which these compounds are removed by allowing them to selectively react
with hydrogen in the presence of a catalyst and a method of removing these compounds
by solvent extraction.
[0004] In such methods, it is known that many metals have an activity for the hydrogenation
reaction of highly-unsaturated hydrocarbon compound. In the case of hydrogenation
reaction carried out in the petrochemical industry to purify olefin compounds, a highly
selective catalyst is required in order to prevent the loss of olefins caused by hydrogenation
of olefin compounds which is a side reaction, and as an appropriate catalyst therefor,
a palladium-based catalyst is used.
[0005] Such palladium-based catalyst used in the selective hydrogenation reaction has not
only high selectivity, but also excellent activity; therefore, by adjusting the reaction
temperature, the catalyst is used while inhibiting side reactions and unreacted highly-unsaturated
hydrocarbon compounds. Yet, when comparing the reactivity for olefin compounds and
acetylene compounds, the palladium-based catalyst has markedly higher reactivity for
acetylene compounds.
[0006] However, since the amount of olefin compounds normally existing in the reaction system
is overwhelmingly greater than that of acetylene compounds, hydrogenation of olefin
compounds also occurs along with hydrogenation of acetylene compounds. From the standpoint
of the yield of a desired compound, it is preferred that the catalyst allow minimal
amount of this hydrogenation reaction of olefin compounds as side reaction. Further,
as another side reaction, precipitation of carbonaceous substances also occurs on
the catalyst due to polymerization of highly-unsaturated compounds. It is, therefore,
also preferred that such precipitation of polymerized substances be minimized as much
as possible since it can reduce the regeneration rate of the catalyst.
[0007] Especially, it is difficult to remove trace amounts of C4 acetylene compounds such
as vinylacetylene and ethylacetylene from a C4 hydrocarbon reservoir mainly containing
1,3-butadiene by hydrogenation, and butadiene is also hydrogenated to generate butane.
However, since butadiene is useful as a polymer raw material and the loss thereof
leads to a large economical loss, it is preferred to minimize such loss as much as
possible.
[0008] So far, as a method of improving the performance of a palladium-based catalyst, it
is reported in Patent Document 1 that the selectivity is improved by adding Ag to
the catalyst composition. In addition, Patent Document 2 reports that the selectivity
is improve by adding Ag and Bi to Pd in the catalyst composition. Further, Patent
Document 3 reports a catalyst in which Te or Sb was added in order to suppress the
elution of Pd into highly-concentrated butadiene flow. However, while the suppression
of Pd elution is described therein, there is no description regarding improvement
of the catalyst selectivity. That is, none of the prior arts could completely remove
C4 acetylenes while maintaining the activity of the palladium-based catalyst for selective
hydrogenation of C4 acetylene compounds at a high level and also in terms of the selectivity
level, without a loss of 1,3-butadiene caused by excessive hydrogenation.
DISCLOSURE OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0010] Those previously reported palladium/alumina catalysts have an improved selectivity
by an addition of a co-catalyst component; however, they have practical problems which
could not be satisfied by the prior arts. As a catalyst which selectively hydrogenates
acetylene compounds contained in a C4 hydrocarbon compound reservoir which was obtained
by steam cracking or the like and mainly contains 1,3-butadiene
; the present invention was made to solve such problems of the prior arts. Therefore,
an object of the present invention is to provide a catalyst having a high selectivity
which is sufficiently satisfactory from the practical standpoint, the catalyst selectively
hydrogenating trace amounts of acetylene compounds contained in a C4 hydrocarbon compound
reservoir mainly containing 1,3-butadiene; a method of producing the catalyst; and
a method using the catalyst.
MEANS FOR SOLVING THE PROBLEMS
[0011] In order to solve the aforementioned problems, the present inventors intensively
studied to discover that a catalyst which hardly hydrogenates 1,3-butadiene, that
is, a highly selective catalyst can be produced by adding a novel co-catalyst component
to a palladium catalyst and reducing it with hydrogen at a high temperature.
[0012] That is, the present invention provides a catalyst hydrogenating acetylene compounds
in 1,3-butadiene, which catalyst is characterized by containing palladium and bismuth,
or palladium, bismuth and tellurium and performing the hydrogenation at a high temperature;
a method of producing the catalyst; and a method of using the catalyst.
EFFECTS OF THE INVENTION
[0013] By using the catalyst according to the present invention, selective hydrogenation
reaction of acetylene compounds such as vinylacetylene and ethylacetylene which are
contained at a trace amount in a C4 hydrocarbon compound reservoir mainly containing
1,3-butadiene can be carried out without losing 1,3-butadiene due to hydrogenation;
therefore, a catalyst having much higher selectivity compared to conventional catalysts;
a method of producing the catalyst; and a method of using the catalyst can be provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014]
[Fig. 1(a)]
Fig. 1(a) shows the physical property of the catalyst according to Example 1 measured
by an XRD measuring apparatus.
[Fig. 1(b)]
Fig. 1 (b) shows the physical property of the catalyst according to Comparative Example
4 measured by an XRD measuring apparatus.
BEST MODE FOR CARRYING OUT THE INVENTION
[0015] The present invention will now be described in more detail.
[0016] The catalyst according to the present invention can be prepared by allowing an inorganic
carrier to support a palladium compound; treating the inorganic carrier with a reducing
agent, followed by drying or calcinating in the air; introducing thereto a metal compound;
drying or calcinating the resultant; and subsequently reducing it at a high temperature
in an air flow containing hydrogen.
[0017] The palladium raw material of the catalyst composition according to the present invention
is not particularly restricted as long as it does not contain a component which is
degraded by a heat treatment and eventually remains on the catalyst to be a catalyst
poison. As such palladium raw material, inorganic and organic compounds, such as palladium
chloride, palladium nitrate, tetrachloropalladium and acetonato palladium, may be
employed, and the amount of palladium supported on the carrier is in the range of
0.01 to 1% by weight based on the total weight of the catalyst composition.
[0018] As the carrier, metal oxides such as alumina, silica, titania and silica-alumina
can be used, and alumina is particularly preferred. Alumina may be used in the form
of a molded product such as a tableted product, cylindrical product, extruded product
or spherical product, and alumina having a surface area in the range of 1 to 3 50
m
2/g may be used.
[0019] Palladium is supported onto the carrier by, for example, a soaking method in which
a support solution containing palladium is prepared and the carrier is soaked thereinto,
a spray method in which a support solution is sprayed to the carrier, or an impregnation
method in which a support solution is prepared at an amount comparable to the amount
of water absorption by the carrier and the carrier is impregnated with the entire
amount of the support solution. After being made to support palladium, the carrier
is reduced after drying or calcination thereof or without drying. The reduction is
carried out with hydrogen or by liquid-phase reduction. In the liquid-phase reduction,
an aqueous solution of a reducing agent such as formalin, sodium formate or hydrogenated
boron can be used, and after the reduction, the carrier is washed with water and dried
or calcinated. Here, the temperature of the calcination or reduction is not particularly
restricted; however, it is in the range of room temperature to 600°C.
[0020] It is desired that palladium be supported on the carrier in an eggshell structure.
When the thickness of the palladium layer from the outer surface of the catalyst is
not greater than 400 µm, the loss of butadiene is small and a high selectivity can
be attained.
[0021] The metal compound used as co-catalyst component of the present invention contains
bismuth and may be used in the form of a nitrate salt thereof, an inorganic salt thereof
such as a chloride salt or an organic salt thereof such as an acetic acid salt. The
content of the bismuth compound is in the range of approximately 0.01 to 10% by weight,
more preferably in the range of 0.1 to 6% by weight, based on the total weight of
the catalyst composition. The weight ratio of the bismuth compound to the palladium
compound is preferably 0.1 to 10, more preferably 0.5 to 8.
[0022] As the co-catalyst component according to the present invention, a tellurium compound
may be further added to the bismuth compound. The tellurium compound may be used in
the form of an oxoacid such as a telluric acid salt, an inorganic salt such as a chloride
salt, or an oxide. The content of the tellurium compound is in the range of approximately
0.01 to 0.1% by weight, more preferably at an amount of approximately 0.01 to 0.05%
by weight, based on the total weight of the catalyst composition.
[0023] The co-catalyst component is supported onto the carrier in the same manner as in
the case of palladium, for example, by a soaking method, spray method or impregnation
method. The aforementioned metal compounds may be supported onto the carrier simultaneously
with palladium, or the co-catalyst component may also be further added to the carrier
already supporting palladium.
[0024] After being made to support these metal catalyst components, the carrier is dried
or calcinated, and then reduced in hydrogen gas flow. Here, the calcination temperature
is not particularly restricted; however, it is in the range of room temperature to
800°C.
[0025] The gas used in the reduction which is an important feature of the present invention
may also contain an inert gas such as nitrogen in addition to hydrogen. The reduction
may be carried out at a temperature in the range of 250 to 600°C, and it is preferably
carried out at a temperature in the range of 300 to 500°C. This reduction carried
out in hydrogen gas flow at a high temperature is critical, and at approximately 150°C,
which is a temperature normally used for reduction, the selectivity is reduced. In
addition, even with an addition of silver to the catalyst component as described in
Patent Document 2, a practically sufficient selectivity cannot be attained by hydrogen
reduction at a low temperature. The reason why a high selectivity is attained by the
reduction at a high temperature is believed to be the generation of compounds such
as PdBi and PdBi
2 due to alloying of Pd and the co-catalyst component caused by the reduction at a
high temperature.
[0026] As a result of the analyses on the catalyst physical properties by X-ray diffraction
(XRD) analysis, when the catalyst according to the present invention containing Pd
and the co-catalyst component was reduced at a high temperature, there was a novel
peak which was not observed when the catalyst was reduced at a low temperature; therefore,
it is believed that an alloy of Pd and the co-catalyst component, Bi, was generated
by the reduction at a high temperature. Since this XRD measurement is based on the
crystalline regularity, information regarding the crystal such as strain and size
can be obtained in addition to the crystal quality. The presence of a different peak
indicates a change in the crystal structure even in the same composition. For example,
generation of an alloy such as PdBi
2 results in a peak at such a position indicating the aforementioned change. In this
manner, the catalyst according to the present invention is intrinsically different
from those known catalysts in that an active component of alloyed metal is generated
by carrying out reduction of the catalyst at a high temperature in hydrogen gas flow.
This novel catalyst having such physical property selectively hydrogenates trace amounts
of C4 acetylenes such as vinylacetylene and ethylacetylene that are contained in a
C4 hydrocarbon compound reservoir containing a large amount of 1,3-butadiene.
[0027] For the selective hydrogenation reaction using the catalyst according to the present
invention, either of a fixed-bed-type reactor or fluidized-bed-type reactor may be
used, and the reaction may also be carried out in any of a gas phase, liquid phase
or mixed phase. In the gas phase reaction, for example, the ratio of the olefin compounds
existing at the reactor outlet can be increased by feeding via the reactor inlet using
a carrier gas a mixture of an acetylene compound and an olefin compound such as 1,3-butadiene,
as well as hydrogen gas, into the reactor to which the catalyst according to the present
invention has already been loaded.
[0028] The C4 hydrocarbon compound reservoir mainly containing 1,3-butadiene in which the
catalyst according to the present invention is used refers to a compound reservoir
which contains butane, isobutane, butene, isobutene, 1,3-butadiene, 1,2-butadiene,
ethylacetylene, vinylacetylene and small amounts of C3 and C5 hydrocarbons, and it
mainly contains 1,3-butadiene at an amount of 30 to 60% and vinylacetylene and ethylacetylene
at an amount of 0.1 to 5%.
[0029] Further, the selective hydrogenation reaction in which the catalyst according to
the present invention is used is optimally carried out under the conditions of: the
reaction temperature at 40 to 100°C; the pressure at 0.5 to 5 MPa; LHSV = 1 to 20h-1;
and hydrogen/acetylenes = 0.5 to 2.
EXAMPLES
[0030] The method according to the present invention will now be described by way of representative
examples thereof; however, the present invention is not restricted thereto.
Example 1
[0031] Added to 1,200 ml of pure water was 18.3 ml of palladium chloride solution (120 g/L),
and 1,000 g of alumina carrier was further added thereto. The thus obtained mixture
was left to stand for 90 minutes and after removing the solution, the resultant was
reduced with 5% Na formate solution at 60°C, washed with water and then dried in the
air to obtain a Pd catalyst. On another front, 4.3 g of bismuth nitrate was completely
dissolved in a solution obtained by adding 15 ml of concentrated nitric acid to 165
ml of pure water. The thus obtained solution was added to the Pd catalyst (300 g),
and the resultant was calcinated at 500°C and subsequently reduced in hydrogen at
350°C to obtain a catalyst. This catalyst had a composition ratio of Pd/Bi=0.2%/0.6%.
[0032] This catalyst was subjected to a measurement by an XRD measuring apparatus. The measurement
was carried out by using a copper anticathode at an output of 40 mA and 45 kV and
a wavelength of 1.54 angstrom. The result is shown in Fig. 1(a). There was a peak
at about 2 =28°, which was not observed in Fig. 1(b) showing peaks for the later-described
catalyst according to Comparative Example 4.
Example 2
[0033] A Pd catalyst was obtained in the same manner as in Example 1. On another front,
2.9 g of bismuth nitrate was completely dissolved in a solution obtained by adding
10 ml of concentrated nitric acid to 170 ml of pure water. The thus obtained solution
was added to the Pd catalyst (300 g), and the resultant was calcinated at 500°C and
subsequently reduced in hydrogen at 350°C to obtain a catalyst. This catalyst had
a composition ratio of Pd/Bi = 0.2%/0.4%.
Example 3
[0034] A Pd catalyst was obtained in the same manner as in Example 1. On another front,
5.6 g of bismuth nitrate was completely dissolved in a solution obtained by adding
20 ml of concentrated nitric acid to 160 ml of pure water. The thus obtained solution
was added to the Pd catalyst (300 g), and the resultant was calcinated at 500°C and
subsequently reduced in hydrogen at 350°C to obtain a catalyst. This catalyst had
a composition ratio of Pd/Bi = 0.2%/0.8%.
Example 4
[0035] To 200 g of sodium chloride aqueous solution (1.2% by weight), 3.7 g of palladium
chloride powder was dissolved and pure water was added to obtain 1,200 g of palladium
aqueous solution. After making the temperature of this solution to be 60°C, 1,000
g of alumina carrier was added and the resulting solution was left to stand for 90
minutes. After removing the solution, the resultant was reduced with 5% Na formate
solution at 60°C, washed with water and then dried in the air to obtain a Pd catalyst.
On another front, 10 g of bismuth nitrate was completely dissolved in a solution obtained
by adding 35 ml of concentrated nitric acid to 145 ml of pure water. The thus obtained
solution was added to the Pd catalyst (300 g), and the resultant was calcinated at
500°C and reduced in hydrogen at 350°C to obtain a catalyst. This catalyst had a composition
ratio of Pd/Bi = 0.2%/1.4%.
Example 5
[0036] Added to 1,200 ml of pure water was 18.3 ml of palladium chloride solution (120 g/L),
and 1,000 g of alumina carrier was further added thereto. The thus obtained mixture
was left to stand for 90 minutes and after removing the solution, the resultant was
put into 1,000 ml of 5% Na formate solution at 60°C, left to stand for 3 hours, washed
with water and then dried in the air to obtain a Pd catalyst. On another front, 4.3
g of bismuth nitrate and 0.162 g of telluric acid were completely dissolved in a solution
obtained by adding 15 ml of concentrated nitric acid to 165 ml of pure water. The
thus obtained solution was added to the Pd catalyst (300 g), and the resultant was
calcinated at 500°C and reduced in hydrogen at 350°C to obtain a catalyst. This catalyst
had a composition ratio of Pd/Bi/Te = 0.2%/0.6%/0.02%.
Comparative Example 1
[0037] Added to 1,200 ml of pure water was 18.3 ml of palladium chloride solution (120 g/L),
and 1,000 g of alumina carrier was further added thereto. The thus obtained mixture
was left to stand for 90 minutes and after removing the solution, the resultant was
put into 1,000 ml of 5% Na formate solution at 60°C, left to stand for 3 hours, washed
with water and then dried in the air to obtain a Pd catalyst. On another front, 0.47
g of silver nitrate was completely dissolved in 180 ml of pure water, and after adding
the thus obtained solution to the Pd catalyst (300 g), the resultant was calcinated
at 500°C to obtain a catalyst. This catalyst had a composition ratio of Pd/Ag = 0.2%/0.1%.
Comparative Example 2
[0038] Added to 1,200 ml of pure water was 18.3 ml of palladium chloride solution (120 g/L),
and 1,000 g of alumina carrier was further added thereto. The thus obtained mixture
was left to stand for 90 minutes and after removing the solution, the resultant was
put into 1,000 ml of 5% Na formate solution at 60°C, left to stand for 3 hours, washed
with water and then dried in the air to obtain a Pd catalyst. On another front, 4.3
g of bismuth nitrate was completely dissolved in a solution obtained by adding 15
ml of concentrated nitric acid to 165 ml of pure water. The thus obtained solution
was added to the Pd catalyst (300 g) and the resultant was calcinated at 500°C to
obtain a PD/Bi catalyst. Further, after completely dissolving 0.14 g of silver nitrate
in 180 ml of pure water, the thus obtained solution was added to the Pd/Bi catalyst
(300 g), and the resultant was calcinated at 500°C to obtain a catalyst. This catalyst
had a composition ratio of Pd/Bi/Ag = 0.2%/0.6%/0.03%.
Comparative Example 3
[0039] Added to 1,200 ml of pure water was 18.3 ml of palladium chloride solution (120 g/L),
and 1,000 g of alumina carrier was further added thereto. The thus obtained mixture
was left to stand for 90 minutes and after removing the solution, the resultant was
put into 1,000 ml of 5% Na formate solution at 60°C, left to stand for 3 hours, washed
with water and then dried in the air to obtain a Pd catalyst. On another front, after
completely dissolving 0.16 g of telluric acid in 180 ml of pure water, the thus obtained
solution was added to the Pd catalyst (300 g), and the resultant was calcinated at
500°C to obtain a catalyst. This catalyst had a composition ratio of Pd/Te = 0.2%/0.03%.
Comparative Example 4
[0040] A catalyst was prepared in the same manner as in Example 1 except for the reduction
temperature. The reduction was carried out with hydrogen at 150°C. This catalyst had
a composition ratio of Pd/Bi = 0.2%/0.6%.
[0041] This catalyst was subjected to a measurement by an XRD measuring apparatus. The measurement
was carried out by using a copper anticathode at an output of 40 mA and 45 kV and
a wavelength of 1.54 angstrom. The result is shown in Fig. 1 (b). As clearly seen
from the figure, there was no peak observed at about 2 = 28°, which was observed for
the catalyst according to Example 1.
Test Example
[0042] Using the catalysts according to Examples 1 and 2 and Comparative Examples 1 to 4,
their performances of selectively hydrogenating acetylene compounds were evaluated
under the following reaction conditions.
(Test Conditions)
[0043]
Amount of catalyst = 30ml
LHSV = 10h-1
Pressure = 2.9 MPa
Reaction temperature = 35°C
Hydrogen / acetylene = 1.0
Recycle ratio = 0.5 to 1.0
The reaction ratio is a ratio at which the post-reaction solution is mixed with the
raw material to dilute the raw material.
Recycle ratio = Amount of post-reaction solution (ml/h) / amount of raw material solution
(ml/h)
(Composition of raw material)
[0044]
Vinylacetylene = 0.3 to 0.5%
Ethylacetylene = 0.13 to 1.16%
1,3-butadiene = 44%
1-butene = 18%
t-2-butene = 5 %
c-2-butene = 4%
i-butene = 24%
N-butane = 4%
(Measurement Method)
[0045] The degree of acetylene conversion was determined by measuring the concentrations
of vinylacetylene and ethylacetylene in the solution before and after the reaction
by gas chromatography and using the following equation.
[0046] 
[0047] The ratio of butadiene loss was determined by measuring the concentration of 1,3-butadiene
in the raw material and the post-reaction solution and using the following equation.
[0048] 
[0049] The test results are shown in Table 1. When compared at the same degree of C4 acetylene
conversion, the catalysts according to Examples 1 and 2 resulted in a smaller 1,3-butadiene
loss than the catalysts according to Comparative Examples 1 to 4, and the catalysts
according to Examples had a higher selectivity.
[0050]
[Table 1]
| |
Recycle=0 |
|
Recycle=0.5 |
|
Recycle=1.0 |
|
| |
Degree of C4 acetylene conversion (%) |
Ratio of butadiene loss (%) |
Degree of C4 acetylene conversion (%) |
Ratio of butadiene loss (%) |
Degree of C4 acetylene conversion (%) |
Ratio of butadiene loss (%) |
| Example 1 |
60.4 |
-0.7 |
72.0 |
0.2 |
83.8 |
2.2 |
| Example 2 |
55.4 |
-1.2 |
67.9 |
-0.9 |
77.5 |
0.9 |
| Example 3 |
56.2 |
-1.1 |
75.1 |
-0.6 |
82.7 |
0.5 |
| Example 4 |
64.0 |
-0.6 |
77.2 |
0.5 |
82.5 |
2.2 |
| Example 5 |
51.8 |
-1.0 |
70.3 |
0.5 |
79.6 |
3.4 |
| Comparative Example 1 |
32.0 |
-0.3 |
50.5 |
2.3 |
59.3 |
4.1 |
| Comparative Example 2 |
53.2 |
-0.1 |
64.0 |
0.9 |
72.1 |
2.7 |
| Comparative Example 3 |
48.1 |
1.3 |
60.3 |
2.4 |
74.7 |
4.0 |
| Comparative Example 4 |
41.8 |
-1.1 |
57.1 |
0.4 |
66.0 |
1.2 |
INDUSTRIAL APPLICABILITY
[0051] The catalyst for selective hydrogenation according to the present invention can selectively
hydrogenate trace amounts of acetylene hydrocarbons contained in a hydrocarbon reservoir
obtained by steam cracking or the like, particularly in a C4 hydrocarbon compound
reservoir from which separation of acetylene hydrocarbons was conventionally very
difficult since a large amount of 1,3-butadiene is contained. At the same time, the
catalyst for selective hydrogenation according to the present invention can prevent
excessive hydrogenation reaction. Therefore, it minimizes the loss of useful resources
and is very advantageous in industrial cracking processes. Further, the catalyst according
to the present invention can drastically reduce the cost for producing a final raw
material for macromolecular chemical industry.